Here is what you need to know.
For gaseous reactions, an INCREASE in P shifts the reaction to the side with fewer moles (because it is trying to occupy a smaller volume as P gets larger). For #1, you have 5 moles on the left, 4 on the right; therefore, an increase in P will shift the equilibrium to the right (products favored). A decrease must do the opposite.
#2 is correct.
#3. C is a solid. Decreasing (or increasing ) C will not affect the reaction as long as there is at least 1 molecule of C in the reaction vessel. So the answer is neither.
#4. Now that you know how to answer #1 you should be able to do #4 easily.